I. Field of the Invention
This invention relates generally to an improvement in engineers' vises or the like, and more particularly to master jaw assemblies for the quick removal and attachment of hard and soft jaws.
II. Discussion of the Prior Art
An engineer's vise is used in metalworking applications. An engineer's vise, like a woodworking vise, is used to hold a work piece. Vises have one fixed jaw and another parallel jaw which is moved towards or away from the fixed jaw by a screw. In an engineer's vise, jaws are made either of hard or soft metal. Hard jaws are available with either a coarse gripping surface or are ground flat and smooth. Hard jaws can lead to deformation and error of the finished work piece if the vise is over-tightened, or if the operator is unskilled or negligent in his handling of the work piece around hard jaws. Soft jaws, in contrast, are usually made of a soft metal such as aluminum, plastic or wood. Soft jaws are used to hold delicate work pieces, and can be cut to hold specially shaped work pieces. Soft jaws are typically discarded or recycled after multiple uses.
Because soft jaws are consumable items, it is desirable that they be susceptible to rapid changeover. This requires that soft and hard jaws be prepared for attachment to both the parallel movable jaw and the fixed jaw of the vise. In the prior art, attachable jaws were typically attached to the parallel movable jaw by bolts, requiring holes be drilled into each detachable jaw. U.S. Pat. No. 4,251,066 (“the '066 patent”) teaches providing a master jaw assembly including a locking jaw having a means providing a dovetail groove along an inner side for receiving a dovetail of approximately the same cross-section on the outer side of a detachable jaw. The detachable jaw is fastened to the locking jaw by providing a weakened section of the locking jaw, such as a slot, extending along the base of the groove intermediate of the tapers. One or more pins connect the tapers on opposite sides of the weakened section for movement toward and away from one another. When the dovetail is inserted into the groove, the detachable jaw is attached to the locking jaw.
The approach of fastening the detachable jaw to the locking jaw after attachment in the '066 patent has manifest problems. First, the assembly of the '066 patent is incapable of front loading the detachable jaw and requires that the detachable jaw be inserted from the side. Second, it weakens the structural integrity of the locking jaw. After repeated use of moving the tapers back and forth, the locking jaw will distort and weaken so as to be unusable for its intended purpose. Third, because the locking jaw is made of a metal of greater strength than a soft detachable jaw, a great deal of force is required to pull the tapers toward each other to securely capture the dovetail of the detachable jaw. This will strain the operator and add to the time necessary to change out the detachable jaw. Fourth, the fastening approach of the '066 patent will still allow the detachable jaw to slip inside the dovetail groove if the pins do not adequately tighten the locking jaw to pull the tapers toward one another. Fifth, because the pins are placed on either side of the weakened segment of the locking jaw, the tapers will bow in the middle so that the groove will not conform to the cross-section of the dovetail.
It is accordingly a principal object of the present invention to provide a vise where the detachable jaws can be more easily fastened or clamped to locking jaw.
Another object of this invention is to provide a vise where the detachable jaws are comparatively inexpensive.
An additional object of the present invention is to provide a vise where the detachable jaw may be front loaded into the locking jaw.
Another object of this invention is to provide a vise where the detachable jaw may be releasably attached to the locking jaw with less time and effort.
Still another object of this invention is to provide a vise where the detachable jaw may be securely attached to the locking jaw.
A further object of this invention is to provide a vise in which a soft detachable jaw need not be provided in standard lengths, but instead may be cut from stock of the length required to mount a particular work piece.
A further object is to provide an attachment for converting an existing vise of this type to a vise adapted to accomplish one or more of the above noted objects.